Sauna Material Guide: Safe Chemicals and Standards in Sauna Construction

As the space closest to the human body among wellness products, the safety of wooden saunas is rooted in the selection of sauna materials. This article will reveal how Alphasauna builds a truly safe, healthy, and non-toxic wooden sauna from the the very beginning, covering aspects such as sauna materials and manufacturing processes.

Why are sauna materials so closely related to health?

It is well known that saunas offer health benefits such as detoxification and relaxation. For those requiring long-term sauna use, the quality of sauna materials is not only related to durability but also directly affects the purity of inhaled air and overall health benefits. When the temperature inside a sauna reaches 70-100°C (158-192°F), any substance containing volatile organic compounds (VOCs), such as paint or adhesives, may accelerate their release.

Therefore, selecting sauna materials is the first line of defense for sauna safety. A safe and reliable sauna cabin must ensure that all sauna materials maintain low or zero VOC release levels under prolonged high temperatures.

Alphasauna production process

From raw timber to finished product, Alphasauna employs a non-toxic production process and strict quality control to ensure your sauna is safe, eco-friendly, and reliable.

Carefully Selected Wood

Wood is the core material for saunas. Alphasauna uses natural, durable solid wood for sauna construction, such as red cedar, Canadian hemlock, and pine. We strictly avoid plywood that may release formaldehyde under high temperatures or chemically treated wood.

Furthermore, Alphasauna sources its wood from premium forests in Canada, the United States, Finland, Switzerland, and other regions. All suppliers hold Forest Stewardship Council (FSC) or Programme for the Endorsement of Forest Certification (PEFC), ensuring our products align with environmental protection and sustainable development from the source.

Cutting and Finger-Jointing Process

Before production, we rigorously inspect all timber, removing sections with visible defects such as knots, cracks, and insect holes, while retaining premium sections for subsequent processing. The timbers are then cut into standard lengths.

For the cut lumber, we employ finger-jointing technology to form longer planks. This technique involves creating interlocking “serrated” structures at the ends of two pieces of wood, which are then bonded with PVA glue to form a longer piece of lumber.

After sanding and polishing the wood and pre-assembling the sauna, we apply wood wax oil or PU varnish to the exterior of the outdoor sauna. This enhances the sauna’s moisture resistance and extends its lifespan. Once inspected and approved, the sauna will be packaged and transported to the customer.

Material Safety Analysis

After understanding the overall production process of sauna cabins, it’s easy to see that certain auxiliary materials are still required to enhance performance and lifespan—such as PVA glue for splicing, wood wax oil or PU paint for exterior protection. Next, we’ll take a closer look at these sauna materials in detail and explore how they are appropriately utilized within safety standards.

High-Temperature Resistant PVA Glue

We understand that the adhesive used FOR bonding wood in sauna interiors comes into direct contact with users, making its safety a key concern for many customers. Alphasauna employs high-temperature-resistant PVA glue for splicing. This water-based adhesive boasts high bonding strength and can stably withstand sauna environments ranging from 90-120℃. After curing, the glue layer forms a robust polymer film, making the joint strength approach or even exceed that of the original wood. Regarding safety, this adhesive has passed SGS’s rigorous formaldehyde-free testing, providing customers with peace of mind.

Wood Wax Oil vs. PU Varnish

For outdoor saunas, Alphasauna applies either wood wax oil or PU varnish as a protective outer layer. What distinguishes these two materials for saunas? How do they compare in safety? How should one choose? These are common concerns among many customers.

For many health-conscious and environmentally conscious users, the safety of the coating used in saunas remains a key consideration. Alphasauna consistently adheres to high standards, ensuring all materials meet international specifications. Among our offerings, the wood wax oil coating is the most popular choice, as it beautifully preserves the natural grain of the wood. Meanwhile, the black water-based PU varnish is highly favored for its elegant, modern aesthetic.

Addressing customer concerns about PU varnish’s environmental impact, Alphasauna employs an eco-friendly water-based formula with extremely low VOC and no pungent odor. More importantly, all coatings are applied exclusively to the sauna’s exterior surfaces, ensuring no direct contact with the high-temperature environment inside. This guarantees long-term safety for your use.

How to Choose an Eco-Friendly and Non-Toxic Sauna

After learning about the sauna materials used in manufacturing, many customers are more concerned about how to select a sauna room with the lowest possible level of chemical substances.

What chemical materials are “necessary but controllable”?

Before selecting a low-chemical sauna cabin, it’s essential to understand that not all chemical sauna materials are harmful. Some are unavoidable during manufacturing but can be safely controlled. Take Alphasauna’s barrel-shaped, square, and olive-shaped saunas as examples. The sauna has three main modules: the front wall, back wall, and side walls. For ease of transportation and customer installation, side walls are shipped as single planks, while front and back walls are delivered in modular sections.

During manufacturing, all individual wood planks can be either finger-jointed or made from whole planks. However, for the front and back wall modules, multiple planks must be joined together with glue to form a large block—the use of glue in this step is unavoidable. Rest assured, we exclusively use formaldehyde-free, high-temperature-resistant PVA glue in all necessary bonding processes. This ensures you can breathe safely under high temperatures and enjoy pure heat therapy.

Opting for Non-Finger-Jointed

As mentioned earlier, adhesive is a necessary yet controllable sauna material in construction. For clients seeking a natural experience and wishing to minimize synthetic materials, choosing sidewalls without finger-jointing is a healthier option. This method involves cutting a whole log into planks without glued joints. It’s worth noting that cedar boards without finger-jointing retain more natural knots in their appearance. In contrast, Japanese cypress and hemlock boards without finger-jointing present a cleaner look. You can choose based on your preference and budget.

Prioritize wood wax oil surface treatment

Second, opt for wood wax oil as the protective coating instead of PU varnish. Wood wax oil is made from plant oils, plant waxes, and natural resins. This coating not only preserves the wood’s natural beauty but also allows it to breathe while providing moisture resistance, resulting in a longer lifespan. More importantly, its entirely natural composition avoids the use of artificial ingredients, making it the perfect choice for safety-conscious customers.

Key Certificate Systems for Selecting Eco-Friendly Saunas

Determining whether a sauna is truly non-toxic and eco-friendly requires more than just checking if it’s labeled “natural materials”. It necessitates a comprehensive assessment of whether the sauna materials used meet international safety certifications in terms of sourcing and manufacturing processes. First, verify that the wood originates from sustainably managed forests with Forest Stewardship Council (FSC) certification, indicating the wood has not undergone chemical preservative treatment and is naturally safe. Second, consider environmental or safety certifications from different countries and regions, such as the EU’s CE certification. This certification ensures the product meets EU safety and environmental requirements.

Ventilate Before and After Use to Maintain Air Purity

Over time, sauna cabins may experience surface aging, coating damage, or dust accumulation and moisture, leading to increased release of residual trace volatile organic compounds (VOCs). Air circulation is the most direct and effective method to reduce any VOC concentration. Below are three steps for pure air in your sauna cabin.

Before Sauna – Ventilation

Before turning on the heater, fully open the sauna door to allow free airflow for 1-2 minutes, replacing the existing air in the sauna.

During Sauna – Keep Ventilation Open

During sauna sessions, ensure all vents openings remain open to promote continuous air circulation and prevent stuffiness and odors.

After Sauna – Thorough Drying

After the sauna, leave the door fully open for at least 30 minutes until all wooden surfaces are completely cool and dry to prevent mold growth.

Conclusion

A good sauna experience should relax the body and purify the mind, not cause worry about lurking chemical smells in the air. Alphasauna firmly believes that the core of a healthy and safe sauna lies in the rigorous standards applied to every sauna material from source to production. We use FSC-certified sustainable wood as our base, strictly adhere to CE safety standards, and uphold the principle of “necessary but controlled” in the use of artificial chemicals like coatings and adhesives. We walk the talk with our commitment: Alphasauna, your healthy guardian.

FAQs

Question1: Is it possible to make a sauna completely “chemical-free”?

Answer: Currently, it’s impossible to achieve 100% chemical-free saunas in commercial production. Even with a solid wood structure, adhesives are still needed for the back panel. However, a “non-toxic, harmless, and odorless” sauna can be achieved through strict material selection and process control.

Question2: How should I choose the most eco-friendly model?

Answer: Prioritize saunas with Non-Finger-Jointed wood, as they offer superior safety and performance. If intended for a bedroom or indoor installation, it’s recommended to ventilate and heat the sauna 2-3 times before first use.

Question3: Does a sauna need regular re-oiling or maintenance?

Answer: Yes, the frequency of oiling depends on usage frequency and ambient humidity. We recommend at least once a year.